Typically, a gas turbine engine includes a plurality of combustor baskets positioned circumferentially about a longitudinal axis of the engine. Each of the combustor baskets typically includes a plurality of nozzles. The nozzles may be separated into different stages and may include pilot nozzles. During operation at full load, all stages of all combustor baskets are typically firing and CO emissions are typically low and within requirements. However, at part loads, a challenge exists to meet current industrial CO emissions requirements while maintaining high efficiency. An improved fuel control system is needed to ensure that the CO emissions requirements are met with relatively high efficiency.
As shown in FIG. 1, gas turbine engines have included fuel control systems formed from a plurality of manifolds for controlling fuel flow to the combustor baskets. For instance, the fuel control system may include a pilot manifold, an A-stage manifold, a B-stage manifold, a C-stage manifold, and a D-stage manifold. Each manifold supplies fuel to all of the nozzles within that particular stage in all of the combustor baskets. The valves positioned inline between the main fuel source and the manifolds control fuel supply to each manifold independently and to all of the nozzles of a particular stage located in the combustor baskets. Closing of a valve reduces fuel flow to all nozzles in that stage in all of the combustor baskets. Thus, all combustor baskets are controlled the same with this system. Thus, this fuel control system can regulate the operation of all combustor baskets between shut-off and 100% full load operation.